If you are looking for a sensor, for about $2000, less if OEM'd into
something else, that is essentially perfect, consider the Ocean
Optics PC2000 or similar things from them (The PC2000 has the
present disadvantage that it requires a PC with an ISA slot).

This is a full visible spectrophotometer with a fiber optics probe. It
has enough resolution to be totally accurate. Only problem is that it
needs a calibration lamp to become "absolute". Once calibrated with
a lamp of known color temperarture, it can, of course, calculate colors and color temperature with any spectral distribution whatsoever.

One could have .... maybe they sell ... software that plots the
color on a CIE diagram, and gives the color nearest color temperature
and how far the green is from a "real" temperature.

I've used lots of these and they are very good and very reliable.

The idea of spending over $3000 for the sensor part of anything
used to adjust TV sets totally boggles the mind. It is simply not needed.

The oceanoptics usb2000 is an absolutely fabulous device. Plugs
into a usb hole and is totally self contained. Among the most sensitive
of all sensors out there. Requires a glass fiber probe that breaks easy.
For pointing at the screen it would also require a light spreader.
Minimum oem cost with fiber is about $2600. Mercury calibration lamp
an additional $600. We have the complete SDK for this device and
i have a couple at work. We would be happy to support this device
if there was enough interest in it.

The sony ixl521 sensor that is inside the unit has been discontinued
and the replacement sensor will not be anywhere near as sensitive.